III. Four important areas related to the management of patients with gastrinomas and other pancreatic endocrine tumors (PET's) were perspectively examined during this time period. III. A. Role of somatostatin receptor scintigraphy (SRS) in patients with PET's. Two studies were undertaken to address this question. Studies to determine sensitivity of SRS and its ability to alter clinical management were performed. III.A.1. SRS sensitivity in localizing gastrinomas. A prospective study in 80 consecutive patients with gastrinomas was done. SRS was the most sensitive modality for detecting primary and metastatic tumors and SRS was equal to all conventional imaging studies combined in sensitivity. III.A.2. SRS's effect on clinical management in gastrinoma. In this prospective study in 122 consecutive patients with gastrinoma, 6 criteria were developed which if SRS fulfilled any one it was determined to have altered management. In 47% of patients the use of SRS altered clinical management. These two studies led to the conclusion that SRS is now the imaging modality of choice for gastrinomas, and likely all PET's except insulinomas, because of their similar somatostatin receptor densities. III. B. Role of reoperation in patients with gastrinomas. Most patients (70%) with gastrinomas are not cured after surgery and the role of reoperation is undefined. In collaboration with Dr. R. Alexander, NCI, 17 such patients underwent reoperation. 30% of the patients had long-term biochemical cure after the second operation leading us to recommend reoperation should be performed in such patients with imageable disease. III. C. Esophageal function in patients with gastrinoma. Esophageal disease occurs in >70% of patients with gastrinomas, however, it is unknown whether esophageal motility abnormalities contribute. 92 consecutive patients with gastrinoma were studied prospectively. 85% of the patients had normal esophageal motility and only 1% had an increased LES pressure. Only 3% had Barrett's esophagus. No correlations existed between the motility result and any clinical parameters. These results show esophageal function is normal in most gastrinoma patients and the incidence of Barrett's mucosa is unexpectedly low despite acid hypersecretion. These results suggest that patients with gastrinoma develop esophageal disease primarily secondary to the high acid and likely have additional protective mechanisms than patients with idiopathic reflux disease that protect against the development of a Barrett's esophagus. III. D. Prolonged hypergastrinemia and colonic neoplasia. It is controversial whether hypergastrinemic increases the frequency or growth of human colonic cancer. Gastrinoma patients have marked longterm hypergastrinemia. To address this question 97 consecutive patients with gastrinoma underwent a colonoscopy. No increased incidence of adenomatous polyps or cancer was found. This data suggest hypergastrinemia even up to 30-fold above normal for up to 10 years is not associated with an increased risk of colon neoplasia.